Gastouni (Greek: Γαστούνη) is a town and a former municipality in Elis, West Greece, Greece. Since the 2011 local government reform it is part of the municipality Pineios, of which it is the seat and a municipal unit. Gastouni is situated in a flat rural area, 5 km from the Ionian Sea. The river Pineios flows into the sea near Gastouni. The town is 6 km (4 mi) south of Andravida, 4 km (2 mi) east of Vartholomio, 11 km (7 mi) northwest of Amaliada and 26 km (16 mi) northwest of Pyrgos. The population of the town was 7,524 in 2001. The Greek National Road 9/E55 (Patras - Pyrgos) and the railway from Patras to Pyrgos pass east of Gastouni. There is a 12th-century Byzantine church in the southwestern quarter Katholiki.